In a spring connector for assuring electrical connection in a medical appliance such as an instillation device which is used in a medical field, for example, waterproofing function for preventing intrusion of liquid such as medicine into the appliance is required. The below described Patent Document 1 discloses a drip-proofing connector for electrically connecting a circuit board of a pulmonic dosing appliance and a cartridge to each other. This drip-proofing connector “includes a hollow body pin 11 which is press-fitted into a mounting hole 2 in a housing 1 to be engaged and fixed there, a movable pin 12 which is reciprocally inserted into this body pin 11, and a coil spring 17 which is interposed between an inner bottom face of the body pin 11 and a bottom face of the movable pin 12” (paragraph [0020] in Patent Document 1), and has such a structure that a drip-proofing cover 20 (silicone rubber or the like) is tightly fitted to an engaging groove 16 on a side face of the movable pin 12 (paragraph [0027] in Patent Document 1).